What cause black spot on skeletal mesh?

[GiadaFranchi]

Hi everyone, I’m having this rendering issue with my skeletal mesh.
I’ve searched everywhere online but haven’t found any effective answers:

• My project is a mobile project, converted from UE 5.4 to UE 5.6.1.

• This issue didn’t exist in UE 5.4.

• Nanite isn’t enabled (I saw some threads mentioning Nanite as a possible cause).

• Right after the conversion, we had problems with inverted normals across the whole project, but those were fixed by disabling “Use DXT5 Normal Maps.” However, that didn’t solve the black patches issue.

• The mesh is skeletal, and the area affected by the black patches is a single piece — there are no overlapping meshes.

Any help would be greatly appreciated, thank you so much!

[brs-sebascova]

Hello there @GiadaFranchi!

From your provided data, those spots are related to migration aftermatch. Something is not working as intended, either the texture maps, or configuration conflicts from the previous version. There are multiple possible causes, we can cover the most likely ones.

For starterts, please make sure your map settings remain in order, specially in the normal maps:

• Check if “Compression Settings” is set to “Normalmap”
• Make sure sRGB is unchecked
• Set “Mip Gen Settings” to “NoMipmaps”

Also, please test disabling “Recompute Normals” from your mesh, which solved a similar issue in the thread below:

Mysterious black blobs on mesh. Help needed

Hey @User-32b1bbcca6 , I found something that works for me. I suspected that it wasn’t a material or texture issue, but related to normals, because the spots were located at the vertices. If I retopologized the mesh and got 100x more vertices, then I got 100x more black or bright white points. So I started looking for a solution along the normals and edges and I found it… at least it helped me. As I wrote, it was also noticeable that the same mesh will only be faulty if I bring it in as a Skel…

Next, since your project comes from mobile, there were a few cases where Skin Cache was causing strange artifacts in meshes:

• Go to Project Settings > Engine > Rendering
• Locate “Support Compute Skin Cache” and turn it off
• If it’s already on, turn it off, restart the editor, and re-enable it, which will force a shader recompile

Finally, you also mentioned Nanite, which was disabled from project settings. Yet, if it was ever used in the mesh with the previous build, there could be residual data lingering on the asset. To ensure that’s not the case, enable Nanite for the bird, apply changes, then un-check it and apply again, which will force the engine to remove any Nanite data still present.